A cable accessory comprising a cold shrinkable terminal and an intermediate joint is an important part of a power transmission cable line. The cold shrinkable terminal is generally applied in a joint of a cable to an electric apparatus, such as a generator, motor, transformer, gas insulation switchgear (GIS), or the like, and the intermediate joint is generally applied in a joint of two cables. The cold shrinkable terminal is used to disperse an electric field at an incision of a conductive shielding layer of the cable and protect the cable from breakdown. The cold shrinkable terminal also prevents moisture and conductive contaminants from entering into an insulation tube and contacting a conductor of the cable, retaining the insulation performance of the joint of the cable and ensuring the long-term safe operation of the cable.
In the prior art, a pre-expanded cold shrinkable terminal for terminating a cable mainly comprises a terminal body, a stress control cone, and an end sealing connection member. The end sealing connection member is hermetically connected to one end of the terminal body. The stress control cone is provided in the terminal body near the other end of the terminal body.
The cable generally comprises a conductor core, an inner insulation layer covered on the conductor core, a conductive shielding layer covered on the inner insulation layer, and an outer sheath layer covered on the conductive shielding layer. Before mounting the cold shrinkable terminal to the cable, one must remove a section of outer sheath layer from the cable to expose a section of conductive shielding layer, remove a part of the exposed conductive shielding layer to expose a section of inner insulation layer, and remove a part of the exposed inner insulation layer to expose a section of conductor core. In this way, a processed cable joint is formed. Then, a layer of grease, for example, silicone oil, is coated on the exposed inner insulation layer of the cable joint. The cold shrinkable terminal is then mounted on the cable joint coated with the layer of grease. After the cold shrinkable terminal is mounted on the cable joint, the grease is filled in a void between the cable joint and the terminal body of the cold shrinkable terminal. The grease filled in the void may effectively reduce the risk of local concentrated discharge and effectively prevent the phenomenon of breakdown.
In another known pre-expanded cold shrinkable terminal, the cold shrinkable terminal comprises a terminal body, a stress control tube provided in the terminal body, and a layer of stress control clay provided in the terminal body. Before mounting the cold shrinkable terminal to a processed cable joint of the cable, the stress control clay and the stress control tube are covered on the exposed conductive shielding layer and the exposed inner insulation layer of the processed cable joint of the cable. In this way, through double layers of stress control material, local concentrated discharge at the processed cable joint of the cable is prevented.
In the prior art, the terminal body of the pre-expanded cold shrinkable terminal is commonly made of silicone rubber material, and a void filling glue containing silicone rubber base material is often used as the stress control clay. As a result, the terminal body and the stress control clay contain the same silicone rubber base material. Since two kinds of materials containing the same base material may affect each other in a case of large expansion ratio, the physical properties of the terminal body may decrease, and the vulcanized terminal body of silicone rubber may easily crack.